Ātmā is nitya-nirmala, ever pure. This means it never mixes with the qualities (gunas) of matter (prakṛti), it is always distinct from matter, factually untouched by it. This is evident from a statement in Bhāgavata Purāna (5.11.12): “The pure self witnesses the activities of the impure mind.”

By Satyanaryana Dasa Part 1: The Nature of Ātmā - Different schools of Indian philosophy and theology present different doctrines regarding the agency, enjoyership and knowership of ātmā, the individual self. Among them, the Vedānta schools accept the authority